1. Field of the Invention
The present invention relates to a video information transmitting apparatus, video information receiving apparatus and video information adjusting apparatus that automatically adjusts the resolution and brightness of video information, for example, according to a user""s condition in a telecommunication system, and thereby achieves efficient utilization of computer resources.
2. Related Art of the Invention
Videotelephones and videoconferencing systems are examples of means of telecommunications that enable persons in remote locations to exchange larger volumes of information between them. In such systems, when shooting a document or the like to be presented to the other party and the expressions of a participant at the transmitting end for transmission, the iris of the camera used for shooting, the shooting environment, etc. are adjusted at the transmitting end.
Many systems have been proposed or put to practical implementation, including multimedia conferencing systems, that are capable of presenting documents and the expressions of conference participants by using a plurality of full-motion windows (windows for displaying moving images).
Such systems enable conferences to be conducted among people in remote locations by displaying the expressions of conference participants and documents to be presented to the participants in a plurality of full-motion windows.
In videotelephones and videoconferencing systems, however, when shooting a person located near a window or a document to be presented to the other party, the transmitting party has to adjust the iris of the camera, etc. by considering the receiving conditions at the receiving end.
Furthermore, in a multimedia conferencing system, participants do not always need to view all the full-motion windows displayed.
In this way, in the previous video information transmission systems, since transmission is performed without considering user conditions, any video information is transmitted in the same way regardless of whether the user""s attention is focused on it or not, and it has been found that this presents a problem in terms of efficient utilization of computer resources.
The present invention performs the adjustment of illuminance information and/or image resolution by using an improved type CCD (solid-state imaging device) described in a previous patent application filed by the present inventor. The improved type CCD means that an improvement is made in the amount of charge transfer in a CCD.
The improved type CCD will be described below.
FIG. 1 is a diagram schematically showing the structure of the improved type CCD by comparison with the structure of the current type. As shown in FIG. 1(1), in the current type CCD, four transfer gates are used for two pixels, so that a signal of only one packet can be transferred for two pixels.
On the other hand, the improved type CCD employs a 2-pixel, 8-gate configuration, as shown in FIG. 1(2) or (3). This configuration allows a signal of a maximum of three packets to be transferred for one pixel. Japanese, Application No. 5-145887 is incorporated herein by reference.
By increasing the number of transfer packets, as shown in FIG. 1(2), signals of two different accumulation periods (for example, different shutter speeds such as {fraction (1/60)} [sec] and {fraction (1/1000)} [sec]) can be read out separately, and by combining these, signals of wider dynamic range can be handled.
NTSC resolution is obtained by mixing photodiode (PD) signals of even-numbered lines and odd-numbered lines. It is already known that if these two kinds of signals are handled separately rather than mixing them together, image resolution can be increased by about 30% (Ishigami, et al., xe2x80x9cxc2xd-inch, 380,000-pixel Whole-Image Readout CCD Imager,xe2x80x9d Technical Report, The Institute of Television Engineers, Vol. 17, No. 16, pp. 39-44 (1993)). This report is incorporated herein by reference.
Therefore, by using the improved type CCD, image resolution can be adjusted according to the situation. If these two resolutions are switched according to the situation, high-resolution images can be obtained without unnecessarily using computer resources (such as network and storage capacities).
FIG. 2 is a diagram showing how subjects of different illuminance levels are imaged by the improved type CCD by comparison with the current type CCD. In the current type CCD, the dynamic range is narrow, and depending on the subject, the outside background may appear xe2x80x9cwhite outxe2x80x9d or the room interior may appear xe2x80x9cblack outxe2x80x9d.
Therefore, in the-current type CCD, the range of illuminance for shooting must be adjusted by using a mechanical iris while viewing the image currently being shot, or by controlling the signal accumulation time by using an electronic shutter.
On the other hand, with the improved type CCD, which has a wide dynamic range, the phenomena of xe2x80x9cwhite outxe2x80x9d and xe2x80x9cblack outxe2x80x9d do not occur.
FIG. 3 is a diagram showing the performance of the improved type CCD. In the improved type CCD, when signals of different accumulation times, such as {fraction (1/60)} [sec] and {fraction (1/1000)} [sec], are read independently of each other, as earlier described, the dynamic range of the CCD increases by a factor of more than 13. Further, if the shutter speed is changed to {fraction (1/100,000)} [sec], the photodiode saturation level increases by a factor of more than 1,300 compared to the prior known type.
FIG. 4 shows images captured using the improved type CCD. The accumulation time is {fraction (1/1,000)} [sec] for a high illuminance image and {fraction (1/60)} [sec] for a standard illuminance image. When the current type CCD is used, both a light bulb and a can having different illuminance levels cannot be presented clearly; on the other hand, when the improved type CCD is used both the character on the can and the character on the light bulb can be presented.
It is therefore an object of the present invention to provide a video information adjusting apparatus that achieves efficient utilization of computer resources by adjusting the resolution and/or brightness of video information, primarily by using the improved type CCD.
To achieve the above objects, the invention provides a video information adjusting apparatus comprising image information acquiring means for separately acquiring image information corresponding at least to two different kinds of illuminance ranges, from an identical shot on the basis of a prescribed imaging condition, and image information generating means for generating brightness-adjusted image information on the basis of a prescribed illuminance range and by using all or part of the image information corresponding at least to the two kinds of illuminance ranges.
Further, to achieve the above objects, the invention provides a video information transmitting apparatus comprising image information acquiring means for separately acquiring image information corresponding at least to two different kinds of illuminance ranges, from an identical shot on the basis of a prescribed imaging condition, and transmitting means for separately transmitting out the image information corresponding at least to the two kinds of illuminance ranges.
More, to achieve the above objects, the invention provides a video information receiving apparatus comprising transmitting means for separately receiving image information corresponding at least to two different kinds of illuminance ranges from outside, and image information generating means for generating brightness-adjusted image information on the basis of a prescribed illuminance range and by using all or part of the image information corresponding at least to the two kinds of illuminance ranges.
Furthermore, to achieve the above objects, the invention provides a video information adjusting apparatus comprising image information acquiring means for separately acquiring image information corresponding at least to two different kinds of illuminance ranges, from an identical shot on the basis of a prescribed imaging condition, transmitting means for separately transmitting out the image information corresponding at least to the two kinds of illuminance ranges, and for receiving other image information corresponding at least to two different kinds of illuminance ranges from outside, and image information generating means for generating brightness-adjusted image information on the basis of a prescribed illuminance range and by using all or part of the other image information corresponding at least to the two kinds of illuminance ranges.
Further, to achieve the above objects, the invention provides a video information adjusting apparatus comprising image information acquiring means for separately acquiring image information of even-numbered lines and image information of odd-numbered lines on a field-by-field basis on the basis of a prescribed imaging condition, transmitting means for receiving information concerning prescribed resolution from outside, and image information generating means for generating image information corresponding to the prescribed resolution by using all or part of the image information of even-numbered lines and the image information of odd-numbered lines.
More, to achieve the above objects, the invention provides a video information transmitting apparatus comprising image information acquiring means for separately acquiring image information of even-numbered lines and image information of odd-numbered lines on a field-by-field basis on the basis of a prescribed imaging condition, and transmitting means for transmitting out the image information of even-numbered lines and the image information of odd-numbered lines separately.
Furthermore, to achieve the above objects, the invention provides a video information receiving apparatus comprising transmitting means for separately receiving image information of even-numbered lines and image information of odd-numbered lines on a field-by-field basis from outside, and for receiving information concerning prescribed resolution from outside, and image information generating means for generating image information corresponding to the prescribed resolution by using all or part of the image information of even-numbered lines and the image information of odd-numbered lines.
Moreover, to achieve the above objects, the invention provides a video information adjusting apparatus comprising image information acquiring means for separately acquiring image information of even-numbered lines and image information of odd-numbered lines on a field-by-field basis on the basis of a prescribed imaging condition, transmitting means for separately transmitting out the image information of even-numbered lines and the image information of odd-numbered lines, and for separately receiving other image information of even-numbered lines and other image information of odd-numbered lines from outside and also receiving information concerning prescribed resolution from outside, and image information generating means for generating image information corresponding to the prescribed resolution by using all or part of the other image information of even-numbered lines and the other image information of odd-numbered lines.